A day or so after my return from my trip to Orleans, The Guardian published an article on deadly algae on Brittany’s beaches. The alga in question is Ulva, which I have written about a few times in the past. It is a genus that is often associated with elevated concentrations of nutrients (see “Venice’s green fringe” and “News from Qingdao …”). In Qingdao, the accumulations of algae caused problems during the 2008 Olympic sailing events but, in Brittany, there have actually been deaths associated with these growths. Although green algae do not produce toxins themselves, the mats are so thick that the algae at the bottom cannot get the light and oxygen they need and so die and rot. However, the thickness of the mats also means that the bacteria involved in breaking down dead plant matter are also starved of oxygen and, under such conditions, they can use sulphate as an energy source. This, however, produces the toxic gas hydrogen sulphide which accumulates until released by, in this case, people stepping on the mats.
The problem in Brittany is concentrated on the north coast, close to where the Seine empties into the English Channel, rather than the south coast, where the Loire joins the Bay of Biscay. Seine or Loire, the problem is similar: France has a large and vociferous farming lobby and inorganic nutrients, much deriving from agriculture, spill out of the rivers into the sea where they encourage the growth of algae. It is not just green algae: there are also toxin-producing dinoflagellate blooms which can render shellfish dangerous for human consumption. The combination of seashores piled high with rotting algae and restaurants unable to source local produce for their “fruits de la mer” is a major worry in a region where tourism makes a significant contribution to the economy. It is also the classic environmental challenge, as economically-rational activities have malign consequences 100 km or more away, creating major headaches for policy-makers.
There is, however, good evidence from modelling studies that a reduction in the nitrogen in rivers that empty into the coast around Brittany will have positive effects. One of these went so far as to envisage the adoption of organic farming in all agricultural areas of the Seine basin, leading to a halving of nitrogen load and a likely very significant reduction in the frequency of dinoflagellate blooms. Another study indicated a likelihood of much less Ulva if river nitrate concentrations were much reduced.
That’s the theory. Putting such reductions into practice is a different matter because it means taking on the farming lobby. There is a simple logic, in a farmer’s eyes, to raising output by adding more of the nutrient that limits growth. The flaw in the argument is that nitrate is highly soluble and a proportion of the nutrient that a farmer spreads on his fields will be washed into nearby water courses when it rains. No farmer wants to pay for fertilizer that is not nourishing his plants so there ought to be a solution that is agreeable to both them and the environment. In reality, implementing policies that protect one sector (seafood harvesting, in this case), whilst not undermining another (agriculture), all within a framework in which market forces drive much of the decision-making is a fiendish challenge.
I think that this is one of the reasons why right-leaning politicians are rarely enthusiastic about the environment: simply leaving market forces to decide outcomes means that “externalities” – consequences of a commercial activity that are not reflected in the price – will be ignored. Environmental regulation implies a need for interventions to control activities in order to protect wider interests, but that is an anathema to free market purists. Regulation should, in theory, limit the “externalities” and create an environment in which sectors such as agriculture, seafood harvesting and tourism can co-exist. Again that’s the theory but regulating the environment invariably results in labyrinthine bureaucracies that soak up money from taxes which free market purists would prefer not to have levied in the first place.
That’s why I really would encourage you to read Kate Raworth’s Doughnut Economics (see “The limits of science …”). Every environmental scientist needs to reflect on how the changes they want to see need structural alterations that permeate throughout society, and not just technological fixes. And, yes, those changes might affect our own lifestyle too. If French farmers use less fertiliser then they will produce less milk per hectare. That, in turn, will result in less of the wonderful French cheeses that we all love and, probably, higher prices. So, in the final analysis, it is not just the use of nitrate fertiliser that will have to change, it is our own aspiration. Before we can make a difference we will have to live differently ourselves. That’s the tough challenge we all have to face.
Passy, P., Le Gendre, R., Garnier, J., Cugier, P., Callens, J., Paris, F., … Romero, E. (2016). Eutrophication modelling chain for improved management strategies to prevent algal blooms in the Bay of Seine. Marine Ecology Progress Series 543: 107-125. https://doi.org/10.3354/meps11533
Perrot, T., Rossi, N., Ménesguen, A., & Dumas, F. (2014). Modelling green macroalgal blooms on the coasts of Brittany, France to enhance water quality management. Journal of Marine Systems 132: 38-53. https://doi.org/10.1016/j.jmarsys.2013.12.010